Device for determining the position of a sliding seat

ABSTRACT

A device that measures the position of a sliding seat used in rowing, canoeing or kayaking. Digitally encoded strips are fixed to the boat and sensors are fixed to a sliding seat such that the sensors detect the encoded strips. A microprocessor analyses the sensor outputs and determines the seat position. The seat position is transmitted from the seat to the boat or other location via a non contact link such as radio.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from the United Kingdom application GB 0418213.5.

The invention relates to a sliding seat in the sports of rowing, canoeing and kayaking.

In the sports of rowing, canoeing and kayaking, sliding seats are often used to allow the athlete to use their legs, in addition to their arms and body, to propel the boat. With the feet fixed in position relative to the boat, the legs can bent during the recovery phase of a stroke and then straightened during the drive phase of the stroke, when the blade or paddle is in the water, such that the legs help to propel the boat.

Such seats are typically mounted on wheels that slide in smooth tracks. This system constrains the movement of the seat to a single dimension and reduces frictional losses.

For the purposes of teaching and high performance coaching it is desirable to be able to measure the position of such a sliding seat as it varies with time.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

The invention relates to a sliding seat in the sports of rowing, canoeing and kayaking. This could apply to water based craft or land based simulators such as rowing machines or ergometers.

In the sports of rowing, canoeing and kayaking, sliding seats are often used to allow the athlete to use their legs, in addition to their arms and body, to propel the boat. With the feet fixed in position relative to the boat, the legs can bent during the recovery phase of a stroke and then straightened during the drive phase of the stroke, when the blade or paddle is in the water, such that the legs help to propel the boat.

Such seats are typically mounted on wheels that slide in smooth tracks. This system constrains the movement of the seat to a single dimension and reduces frictional losses.

For the purposes of teaching and high performance coaching it is desirable to be able to measure the position of such a sliding seat as it varies with time. From this data the velocity and acceleration of the seat at any time can be derived. Such a device should provide a single linear measurement from a known point. This is sufficient to define the position of the seat in space.

It would be undesirable for the device to alter the forces required to move the seat since this would change the characteristics of the rowing boat and alter the performance of the athlete. This requirement rules out a lot of conventional contact methods of determining position due to frictional forces.

An obvious solution to the need for a non-contact sensor would appear to be an ultrasonic range finder. This however is not a practical solution due to complications from spurious reflections from the user's body.

A further problem is that if a sensor is to be mounted on the sliding seat, a method of transmitting data from the sensor to the boat or fixed structure of a rowing machine is required. Again this must not interfere with the characteristics of the system.

A further problem is one of space and weight limitations. Any sensor that is to be fitted to a sliding seat must be lightweight in order not to interfere with the characteristics of the system and is constrained on dimensions due to the geometry of the seat and slide rail system.

BRIEF SUMMARY OF THE INVENTION

The object of this invention is to provide a device that will accurately determine the position of a sliding seat as it varies with time, without interacting with the mechanical characteristics of the sliding seat system.

The invention uses an encoded strip which is attached to the boat or rowing machine and a sensor arrangement which is attached to the underside of the sliding seat. The sensor arrangement includes a microcontroller that monitors the encoded pattern on the strip and determines the position of the sliding seat. This data is then transmitted via a radio link to the boat or fixed structure.

The advantages of this system are that the seat position is determined by a reliable non-contact method. The precision of the measurement can be set by altering the geometry of the encoded strip. The mass of the seat sensor arrangement is sufficiently low to have negligible effect on the characteristics of the system. No wires or other material interfaces are needed to retrieve the seat position data from the sensor arrangement. The encoded strip can be located as an integral part of the slide rails that support the seat. This feature allows the system to be fitted to a boat or rowing machine without encroaching on the space needed by the rower or altering the geometry of the boat and seat in any significant way.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 shows a sliding seat and the invention in plan view

FIG. 2 shows the detector and encoded strip in side view

FIG. 3 shows the detector as a functional block diagram

FIG. 4 shows an alternative arrangement in side view

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention there is provided a device for determining the position of a sliding seat comprising,

One or more encoded strips attached to a boat or part of a boat, one or more sensors attached to a sliding seat such that the sensors detect the encoded strip and provide one or more channels of encoded information, and a method a transmitting the output of the sensor(s) from the seat to the boat or other location.

Preferably a detector is fixed to the seat comprising sensors and supporting electronic circuits, a microcontroller, a power source and a transmission method.

Preferably a receiver, designed to detect the signal transmitted from the seat is fixed to the boat.

In other embodiments a receiver, designed to detect the signal transmitted from the seat is fixed to another boat, shore station or other location.

Encoded strips are attached to the boat, the rails that the sliding seat runs in or a support bracket.

Encoded strips are mounted at any angle to the horizontal in order to suit the design.

A single channel of digital encoded information may be used to determine the speed of a sliding seat.

Two channels of digital encoded information may be used to determine the speed and direction of movement of a sliding seat.

Three channels of digital encoded information may be used to determine the speed, direction of movement of a sliding seat and to fix the position of the seat in absolute terms as it passes a given point.

Multiple channels of digital encoded information may be used to determine the absolute position of a sliding seat by providing a unique output combination for each potential position of the seat.

In one embodiment each channel of digital encoded information is provided by a single sensor and single encoded strip.

In another embodiment multiple channels of digital encoded information are provided by multiple sensors and a single encoded strip.

Preferably the encoded strip comprises sections with properties that are good and poor infra-red reflectors and the sensor comprises an infra-red source and detector.

In another embodiment the encoded strip comprises sections of high and low magnetic field and the sensor is a hall effect sensor.

Preferably the encoded strip and sensor are a non-contact method of digital encoding.

In another embodiment one or more analogue strips, with varying properties along the length of he strip are used to determine the seat position.

Preferably the method of transmitting the sensor output from the boat is a non-contact method.

Preferably the method of transmitting the sensor output from the boat is a radio link, ultrasonic link or infra-red link.

In one embodiment raw data from the sensors is transmitted from the seat.

In another embodiment the microcontroller analyses the sensor output(s) and converts this information to a value representative of the distance of the seat from a known point and this value is transmitted from the seat.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing.

Referring to the drawing a seat [3] has wheels [4] which run on tracks [2] which are in turn attached to a boat [1].

A detector [5] is attached to the underside of the seat and a receiver unit [6] is attached to the boat at a convenient location. Three encoded strips [7,8,9] are fixed to the boat using adhesive tape such that they are parallel to the direction of motion of the seat and cover the full range of movement of the seat. The encoded strips comprise a pattern of black and white sections in which the black sections are a poor reflector of infra-red radiation and the white sections are a good reflector of infra-red radiation. The size of these sections is chosen to give the required resolution. Three sensors [10,11,12] each comprise an infra-red emitting diode and a phototransistor and are mounted on the detector such that they are above the three encoded strips [7,8,9] respectively.

Referring to FIG. 3, the three sensors are connected to a processing circuit [13]. This circuit provides produces power to the infra-red emitting diode and provides a low or high voltage output depending on the state of the phototransistor. Thus three output signals are obtained which correspond to whether each of the three sensors is above a white or black section of the encoded strip. A battery power source [15] provides power to the electrical circuits.

A microcontroller [14] converts the three output signals into a single value that is representative of the seat position. From a single sensor output, the speed of the seat can be determined. From a second sensor output, both speed and direction can be determined. Encoded strips [8] and [9] are used to determine speed and direction of the seat by relative encoding. FIG. 1 shows that encoded strips [8] and [9] are alternate black and white sections. Furthermore they are positioned longitudinally relative to one another such that only one sensor output changes state at any one time. This is done in order to prevent glitches. As the seat moves over the encoded strip the output pattern from sensors [8] and [9] will be as follows (low-low), (low-high), (high-high), (high-low). The microcontroller detects changes in output state and increments or decrements a parameter representative of the distance of the seat from a known point. The third sensor represents the state of encoder strip [7] and is used to fix the absolute position of the seat. Encoder strip [7] is black except for a single section of white at a known location. Thus every time the seat passes this known point sensor [10] provides a high signal to the microprocessor and the distance parameter is set to a value representative of this position. The distance parameter is transmitter from the seat to the boat via a radio link. The microprocessor provides a pulse code modulated signal to a radio transmitter [16] which is connected to an aerial [17]. The receiver [6] (attached to the boat) detects the radio signal and converts the pulse modulated signal back into the distance parameter.

In another example, three infra-red sensors [18,19,20] are mounted on the seat in a line along the direction of travel of the seat. A single digital encoded strip [21] of black and white sections is fixed to the boat such that each of the three sensors are over the encoded strip. FIG. 4 shows the arrangement. The pattern of encoding is arranged such that at one seat position a unique combination of the three sensor outputs is obtained [22]. This allows absolute location of the seat at this point. At all other seat positions [23], two of the sensor outputs are used to determine the relative movement of the seat, both in terms of speed and direction. This arrangement has the advantage of reducing the width of encoded strip required. This is useful since many boat designs have limited space in this area.

In another example a single encoded strip is used in which the infra-red reflective properties increase continuously along the length of the strip. An infra-red transmitter emits a constant level of radiation. A receiver on the seat measures the magnitude of the reflected pulse thus determining the reflectivity of the strip at that position. The measured reflectivity corresponds to a unique seat position.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon. 

1. A device for determining the position of a sliding seat comprising, one or more encoded strips attached to a boat or part of a boat, one or more sensors attached to a sliding seat such that the sensors detect the encoded strip and provide one or more channels of encoded information, and a method a transmitting the output of the sensor(s) from the seat to the boat or other location.
 2. A device for determining the position of a sliding seat according to claim 1, in which a detector is fixed to the seat comprising sensors and supporting electronic circuits, a microcontroller, a power source and a transmission method.
 3. A device for determining the position of a sliding seat according to claim 1, in which a receiver, designed to detect the signal transmitted from the seat is fixed to the boat.
 4. A device for determining the position of a sliding seat according to claim 1, in which the encoded strips are attached to the boat, the rails that the sliding seat runs in or a support bracket.
 5. A device for determining the position of a sliding seat according to claim 1, in which the encoded strips are mounted at any angle to the horizontal in order to suit the design.
 6. A device for determining the position of a sliding seat according to claim 1, in which a receiver, designed to detect the signal transmitted from the seat is fixed to another boat, shore station or other location.
 7. A device for determining the position of a sliding seat according to claim 1, in which a single channel of digital encoded information is used to determine the speed of a sliding seat.
 8. A device for determining the position of a sliding seat according to claim 1, in which two channels of digital encoded information are used to determine the speed and direction of movement of a sliding seat.
 9. A device for determining the position of a sliding seat according to claim 1, in which three channels of digital encoded information are used to determine the speed, direction of movement of a sliding seat and to fix the position of the seat in absolute terms as it passes a given point.
 10. A device for determining the position of a sliding seat according to claim 1, in which multiple channels of digital encoded information are used to determine the absolute position of a sliding seat by providing a unique output combination for each potential position of the seat.
 11. A device for determining the position of a sliding seat according to claim 1, in which each channel of digital encoded information is provided by a single sensor and single encoded strip.
 12. A device for determining the position of a sliding seat according to claim 1, in which multiple channels of digital encoded information are provided by multiple sensors and a single encoded strip.
 13. A device for determining the position of a sliding seat according to claim 1, in which the encoded strip comprises sections with properties that are good and poor infra-red reflectors and the sensor comprises an infra-red source and detector.
 14. A device for determining the position of a sliding seat according to claim 1, in which the encoded strip comprises sections of high and low magnetic field and the sensor is a hall effect sensor.
 15. A device for determining the position of a sliding seat according to claim 1, in which the encoded strip and sensor are a non-contact method of digital encoding.
 16. A device for determining the position of a sliding seat according to claim 1, in which one or more analogue strips, with varying properties along the length of he strip are used to determine the seat position.
 17. A device for determining the position of a sliding seat according to claim 1, in which the method of transmitting the sensor output from the boat is a non-contact method.
 18. A device for determining the position of a sliding seat according to claim 1, in which the method of transmitting the sensor output from the boat is a radio link, ultrasonic link or infra-red link.
 19. A device for determining the position of a sliding seat according to claim 1, in which raw data from the sensors is transmitted from the seat.
 20. A device for determining the position of a sliding seat according to claim 1, in which a microcontroller analyses the sensor output(s) and converts this information to a value representative of the distance of the seat from a known point and this value is transmitted from the seat. 